A rotary electrical machine of this type is known through the French patent number 2 737 063, to which reference can be made for more details. So that the voltages produced by the two three-phase windings, one connected in a star and the other connected in a delta, are identical, it is indicated that the turns of the delta winding must be √3 times the number of the turns on the star winding. It is also stated that the ratio of the cross sections of the turns of the two windings must be 1/√3.
The prior art is thus limited to stating a few specific positive effects procured by the composite winding stator device.